javax.servlet.jsp.tagext
Interface Tag

All Superinterfaces:

JspTag

All Known Subinterfaces:

BodyTag, IterationTag, LoopTag

All Known Implementing Classes:

ActionListenerTag, AttributeTag, BodyTagSupport, BundleTag, BundleTag, CatchTag, ChooseTag, ConditionalTagSupport, CoreForEachTag, CoreForTokensTag, CoreImportTag, CoreOutTag, CoreParamTag, CoreParamTag, CoreRedirectTag, CoreSetTag, CoreSetTag, CoreUrlTag, CoreWhenTag, FmtParamTag, FmtParamTag, FmtParseDateTag, FmtParseNumberTag, FmtRequestEncodingTag, FmtSetTimeZoneTag, FmtTimeZoneTag, FmtTimeZoneTag, ForEachTag, FormatDateTag, FormatDateTag, FormatNumberTag, FormatNumberTag, ForTokensTag, I18NSupport, IfTag, IfTag, ImportTag, IntegerLoopSupportTag, IteratorLoopSupportTag, JspTagFileSupport, LoadBundleTag, LoopTagSupport, MessageTag, MessageTag, OtherwiseTag, OutTag, ParseDateTag, ParseNumberTag, PhaseListenerTag, RedirectTag, RemoveTag, RequestEncodingTag, SetBundleTag, SetBundleTag, SetLocaleTag, SetLocaleTag, SetPropertyActionListenerTag, SetTimeZoneTag, SqlDateParamTag, SqlDateParamTag, SqlParamTag, SqlParamTag, SqlQueryTag, SqlQueryTag, SqlSetDataSourceTag, SqlSetDataSourceTag, SqlTransactionTag, SqlTransactionTag, SqlUpdateTag, SqlUpdateTag, TagAdapter, TagSupport, UrlTag, ValueChangeListenerTag, WhenTag, XmlForEachTag, XmlIfTag, XmlOutTag, XmlOutTag, XmlParamTag, XmlParamTag, XmlParseTag, XmlParseTag, XmlSetTag, XmlTransformTag, XmlTransformTag, XmlWhenTag

public interface Tag
extends JspTag

Tags are Java classes implementing JSP Tag extensions. The class must have a null argument public constructor and implement the tag attribute as setXXX methods, following the Beans spec.

 MyTag tag = new MyTag();

 tag.setPageContext(page);
 tag.setParent(...);
 tag.setFoo(...);
 tag.setBar(...);
 if (tag.doStartTag() == EVAL_BODY_INCLUDE) {
   ...
 }
 if (tag.doEndTag() == SKIP_PAGE)
   return;
 ...
 tag.setParent(...);
 tag.setFoo(...);
 if (tag.doStartTag() == EVAL_BODY_INCLUDE) {
   ...
 }
 if (tag.doEndTag() == SKIP_PAGE)
   return;
 ...
 tag.release();
 









Field Summary




static int
EVAL_BODY_INCLUDE



           



static int
EVAL_PAGE



           



static int
SKIP_BODY



           



static int
SKIP_PAGE



           


 



Method Summary




 int
doEndTag()



          Callback to handle the end of a tag.



 int
doStartTag()



          Callback to handle the start of a tag.



 Tag
getParent()



          Returns the containing tag.



 void
release()



          Cleans up the tag at the end of the page.



 void
setPageContext(PageContext page)



          Sets the page context of this page.



 void
setParent(Tag t)



          Sets the containing tag.


 





Field Detail



SKIP_BODY
static final int SKIP_BODY


See Also:
Constant Field Values




EVAL_BODY_INCLUDE
static final int EVAL_BODY_INCLUDE


See Also:
Constant Field Values




SKIP_PAGE
static final int SKIP_PAGE


See Also:
Constant Field Values




EVAL_PAGE
static final int EVAL_PAGE


See Also:
Constant Field Values





Method Detail



setPageContext
void setPageContext(PageContext page)

Sets the page context of this page.











setParent
void setParent(Tag t)

Sets the containing tag.











getParent
Tag getParent()

Returns the containing tag.











doStartTag
int doStartTag()
               throws JspException

Callback to handle the start of a tag.

 
doStartTag can assume setPageContext,
 setParent, and all tag attribute properties have
 been called.






Returns:
SKIP_BODY to ignore the body and EVAL_BODY_INCLUDE
 to evaluate the body.
Throws:
JspException





doEndTag
int doEndTag()
             throws JspException

Callback to handle the end of a tag.






Returns:
SKIP_PAGE to skip the rest of the page and
 EVAL_PAGE to continue with the rest of the page.
Throws:
JspException





release
void release()

Cleans up the tag at the end of the page.  The same tag instance
 might be reused for multiple tags in the page.